1. Field
The present disclosure relates to the field of a multicarrier optical communication system, and in particular to an apparatus for estimating channel spacing, an apparatus for monitoring wavelength and a receiver.
2. Description of the Related Art
In a multicarrier optical communication system, subcarrier data are modulated in several optical carriers independent of each other. Under an ideal condition, wavelengths of lasers are stable, and spacing of wavelengths of the carriers is constant. In a practical system, as wavelengths of lasers are influenced by variation of driving currents, temperature fluctuation, and resonant cavity aging, etc., output carrier wavelengths drift in a certain range. Such indefinite variation of wavelengths brings relatively large influence to the multicarrier optical communication system, which is mainly embodied in: 1) occurrence of neighboring channel crosstalk between channels of the subcarriers; and 2) edge subcarriers being subjected to more severe distortion.
An effective wavelength monitoring method is an important means for overcoming drift of laser wavelengths. On a basis of monitoring wavelengths, the wavelengths of the lasers may be adjusted with respect to feedback, so as to avoid variation of wavelengths to a great extent, thereby achieving locking of wavelengths of the subcarriers. Stable wavelengths of subcarriers can not only avoid neighboring channel crosstalk, but also make spectrum resources being used more efficiently, thereby improving spectrum utilization.
It should be noted that the above description of the background is merely provided for clear and complete explanation of the present disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present disclosure.